Tuning the gel size and LCST of N-isopropylacrylamide nanogels by anionic fluoroprobe

Abstract

Varying size fluorescent N-isopropylacrylamide (NIPAM) nanogels were synthesized from 140 to 550 nm by precipitation copolymerization. N,N-methylenebisacrylamide (BIS) and ammonium persulfate APS were used as crosslinker and initiator, respectively. 8-Hydroxypyrene-1,3,6-trisulfonic Acid (Pyranine, Py) molecules were used for controlling the particle size and lower critical solution temperature (LCST) of nanogels. NIPAM, BIS and APS amount were kept constant and Py amount changed to tailor the particle size. Fluorescence spectroscopy, atomic force microscopy and light scattering methods show that Py caused smaller size nanogels due to the electrically charged SO − 3 side groups. Additionally, as seen from the light scattering experiment, LCST of nanogels is getting decrease considerably with increasing Py amount. Using of Py for tuning, the gel size and LCST were found very useful, easy and effective way, and it can be used for many biomedical applications.

Preparation of thermosensitive PNIPAm‐based copolymer coated cytodex 3 microcarriers for efficient nonenzymatic cell harvesting during 3D culturing

“…As shown in Figure 4a,b, when the percentage of AAc or AAm that copolymerized with NIPAm were increased, the LCST temperature of the copolymer was shifted to the higher values. This is due to the hydrophilic nature of AAc and AAm and thus, the copolymer solution requires higher temperature for phase transmission and enabled the copolymer to be aggregated (Katsumoto et al, 2002). The cloud point of PNIPAm‐ co ‐AAc 1 , PNIPAm‐ co ‐AAc 3 , and PNIPAm‐ co ‐AAc 5 were shifted to 29.5°C, 30°C and 32°C, respectively, indicating that increasing the ratio of the AAc increases the LCST of the copolymer solution.…”

Preparation of thermosensitive PNIPAm-based copolymer coated cytodex 3 microcarriers for efficient non-enzymatic cell harvesting during 3D culturing

“…However, its LCST value is lower than body temperature which ranges from 30 to 32 degC, irrespective of polymer concentration. In order to raise the LCST of the polymer, frequently hydrophilic polymers are incorporated in the copolymer or increase the proportion of hydrophilic to hydrophobic components in the copolymer and have been shown to elevate the LCST of PNIPAm (Jain, Vedarajan, Watanabe, Ishikiriyama, & Matsumi, 2015;Koc & Alveroglu, 2016;Osvath & Ivan, 2017). Therefore, in this study, NIPAm was copolymerized with hydrophilic acrylic acid (AAc) or acrylamide (AAm) at different ratios to prepare a thermo-responsive PNIPAm-co -AAc with optimized LCST value near to body temperature.…”

Nanogels as potential drug nanocarriers for CNS drug delivery

“…Modulating their surface and size properties to respond to the various different pH levels inside the human body enables them to be delivered via different routes to target different organs. Nanogels have also gained significant attention because of their ability to respond to external stimuli, such as ionic strength [32], temperature [33], pH [34], and magnetic [35] and electric fields [36]. These nanocarriers respond to these stimuli by changing properties, such as by swelling or shrinking to change their volume, their flexibility, and refractive index.…”